Lorenza Zambon, actress and gardener, tells the story of a couple who decided to demolish some property of theirs and return the area to fertile soil. A few square meters gained, about one trillion still to recover.

It is not easy to determine the area of the world covered by human-made artifacts, that is by roads, houses, parkings, buildings, commercial centers and all the rest. But much work has been performed in recent times and the estimates are starting to converge on reasonable values. The results for the fraction of area covered with permanent structures range from about 0.5% (Schneider et al., 2009) to about 3% (Global Rural-Urban Mapping Project, 2004). Translated into areas, these values correspond to a minimum of 700,000 square km and to a maximum of about three million square km. To visualize these areas, think that the first one compares to France (550,000 square km) and the second to India (3.2 million square km).

No matter which result we should consider as the most reliable, the data clearly show that building takes place mostly in flat and fertile areas. There, the fractions covered by human-made structures are much larger than the world average. For instance, recent data for Europe indicate that, in January 2012, the most urbanized European states were Holland and Belgium with, respectively, 13.2% and 9.8% of the surface. As you see below (From Schneider et al.), urbanization in Europe is, indeed, concentrated in the fertile plains. Apparently, we are engaged in the task of destroying the land that supports our physical existence.

We have no data telling us how fast this paving of land has been going on up to now but, if it is proportional to the production of cement, growth has been spectacular (data from USGS).

It is impressive that the curve shows no sign of abating whatsoever. Maybe there will be a peak in the coming years, but cement is a form of "persistent pollution." Reducing its production - or even stopping it - won't automatically return built environment to fertile soil. But we can't eat concrete. Will we ever get our land back?

Restoring to fertility land covered with concrete is an enormous task, but not an impossible one. So, Lorenza Zambon, actress and gardener, tells the story of a couple in Turin, Italy, who decided to give to their children a patch of fertile land as a gift. They obtained it by demolishing a few concrete garages they had inherited.

It was a lot of work; concrete had to be cut and broken to pieces and the rubble carried away. Then, restoring the fertility of the soil took truckloads of dirt, charcoal, and more. Zambon doesn't tell us how long the task took nor how much it cost, but surely it was slow, messy and expensive. It was also a subversive idea: in the generally accepted view, paving the land means "developing" it, and that means making money. So, destroying property to restore the fertile soil is something that nobody in his/her right mind would - normally - do.

But someone did it. The end result was a patch fertile soil where grass and flowers grow. Just a few tens of square meters, not much in comparison to the trillion remaining to be recovered. But it is a first step!

This post was inspired by a talk given by Lorenza Zambon in Florence on March 24, 2012. If you want to hear Lorenza speaking on these matters, you can find one of her presentations here, unfortunately it seems that she does that only in Italian.